I've ridden old Carafino, Lift, Spotz, Sword and Alpine foils (maybe one or two others here and there), and the Alpine is my favorite for free riding (I have not raced them yet). Very well built and produced, great hydrodynamics, very stable but also turn well, and you can foil quite slow and pretty damn fast - which is what you want for free riding.
In my experience:
Lift is a very solid foil, rides well, cheapest, very nice carbon boards, but not as smooth and not as stable.
Sword has great feel, good roll-axis turns like Alpine but shorter longitudinal axis makes for slightly more twitchy feel. May be faster, however – several guys compete very successfully on Swords.
Spotz is most twitchy, especially their race wing. More 'square' profile. Not as fun for me, for free riding, but by far the most common foil amongst racers here in San Francisco.
Alpine is (for me) smoothest, most stable and also most fun ride. Feels like a 787 Dreamliner to me
I'm not sure why people think the Alpinefoil is expensive; the list price is something like €1662 outside of France, which is $2077 right now, and the Sword is $2650!